Method for calculating fouling layer drying rate, calculation device and computer-readable medium

Abstract

The present invention provides a method for calculating the burnout rate of a fouling layer, a calculation device, and a computer-readable medium, which solves the problem that the existing method for calculating the burnout rate of a fouling layer is inaccurate. The method for calculating the burnout rate of a fouling layer includes: sequentially dividing the fouling layer from the fouling surface to the wall surface; setting the interior of the fouling as a capillary porous structure and setting the parameter boundary values on the fouling surface; constructing a set of relational expressions for calculating flow and heat transfer parameters, and calculating the flow and heat transfer parameters of each fouling layer according to the set of relational expressions and the parameter boundary values on the fouling surface; judging whether the current fouling layer is a burnout position according to the flow and heat transfer parameters, and if so, obtaining the thickness of the current fouling layer, and calculating the burnout rate of the fouling layer according to the thickness of the current fouling layer and the total thickness of the fouling layer.

Description

Technical Field

[0001] The present invention mainly relates to the technical field of nuclear reactors, and particularly relates to a method for calculating the burnout rate of a fouling layer, a calculating device, and a computer-readable medium. Background Art

[0002] Corrosion products (also known as fouling) released from the primary loop system of a pressurized water reactor will deposit on the surface of the fuel cladding. A large amount of fouling deposition can not only cause crud-induced power shift (CIPS), but also lead to a local temperature increase on the surface of the fuel cladding, thereby accelerating the oxidation of the cladding. In severe cases, it can cause the corrosion failure of the fuel cladding. Crud-induced localized corrosion (CILC) of the fuel cladding is one of the important reasons for fuel rod failure.

[0003] The burnout rate of the fouling layer is an important indicator for evaluating the CILC risk in the fouling risk analysis of the reactor core. The burnout rate of the fouling layer refers to the ratio of the thickness of the dried-out part of the fouling to the total thickness of the fouling. Therefore, there is an urgent need to provide a method for calculating the burnout rate of the fouling layer required for fouling risk analysis. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for calculating the burnout rate of a fouling layer, a calculating device, and a computer-readable medium, so as to solve the problem that the existing method for calculating the burnout rate of the fouling layer is inaccurate.

[0005] To solve the above technical problem, the present invention provides a method for calculating the burnout rate of a fouling layer, including: sequentially dividing the fouling layer from the fouling surface to the wall surface; setting the interior of the fouling as a capillary porous structure and setting the parameter boundary values on the fouling surface; constructing a set of relational expressions for calculating flow and heat transfer parameters, and calculating the flow and heat transfer parameters of each fouling layer according to the set of relational expressions and the parameter boundary values on the fouling surface; judging whether the current fouling layer is a burnout position according to the flow and heat transfer parameters. If so, obtaining the thickness of the current fouling layer, and calculating the burnout rate of the fouling layer according to the thickness of the current fouling layer and the total thickness of the fouling layer.

[0006] Optionally, the flow and heat transfer parameters include the mass evaporation rate, temperature, and critical pore radius, and the set of relational expressions includes: the momentum conservation equation, the energy conservation equation, and the interphase heat transfer equation.

[0007] Optionally, the momentum conservation equation is:

[0008]

[0009] Wherein, is the liquid surface tension, is the contact angle, R* is the critical pore radius, P is the pressure, and the subscripts l and v represent the liquid phase and the vapor phase, respectively. is the grid size.

[0010] Optionally, the energy conservation equation is:

[0011]

[0012] where is the heat flux under the heat conduction of the (n + 1)-th layer, is the heat flux under the heat conduction of the n-th layer, is the mass evaporation rate of the (n + 1)-th layer, is the mass evaporation rate of the n-th layer, is the enthalpy value of the vapor phase on the fouling surface, is the enthalpy value of the liquid phase on the fouling surface.

[0013] Optionally, the temperature of each fouling layer is calculated by the following formula:

[0014]

[0015] where is the thermal conductivity of the fouling layer, is the temperature of the fouling layer, is the grid size.

[0016] Optionally, the thermal conductivity of the fouling layer is calculated by the following formula:

[0017]

[0018] where is the porosity of the (n + 1)-th layer, is the proportion of the liquid phase in the fouling layer of the (n + 1)-th layer, k is the thermal conductivity, and the subscripts l, v, and s represent the liquid phase, the vapor phase, and the solid phase in the fouling layer, respectively.

[0019] Optionally, based on Darcy's law of porous media, the proportion of the liquid phase in the fouling layer is a variable value.

[0020] Optionally, the interphase heat transfer equation is:

[0021]

[0022] where is the volumetric heat transfer coefficient of the phase change, is the saturation temperature of the liquid inside the fouling, is the temperature of the fouling layer, is the latent heat of vaporization, is the mass evaporation rate, is the grid size.

[0023] Optionally, when the mass evaporation rate of the fouling layer is lower than a first threshold and the fouling layer temperature is higher than a second threshold, it is determined that the fouling layer is the dry-out position.

[0024] Optionally, it further includes: during the process of calculating the flow and heat transfer parameters, judging the convergence and rationality of the calculation results according to physical laws, so as to save the number of iterations in the calculation process.

[0025] Optionally, it further includes: dynamically adjusting the grid size during the process of calculating the flow and heat transfer parameters.

[0026] Optionally, the parameter boundary values of the fouling surface include: the temperature of the fouling surface, the critical pore radius, the critical pore radius gradient, and the mass evaporation rate gradient.

[0027] To solve the above technical problems, the present invention provides a computing device, including: at least one processor; and at least one memory, on which instructions are stored, and when the instructions are executed alone or jointly by the at least one processor, the computing device is enabled to execute the method as described above.

[0028] To solve the above technical problems, the present invention provides a computer-readable medium, on which instructions are stored, and when the instructions are executed alone or jointly by at least one processor of a computing device, the computing device is enabled to execute the method as described above.

[0029] Compared with the prior art, the present invention has the following advantages:

[0030] The present invention provides a dry-out rate analysis method for a fouling layer required for fouling risk analysis. This method divides the fouling layer from the fouling surface to the wall surface in sequence, considers that the interior of the fouling is a capillary porous structure, and considers the capillary action in the pores, assumes the parameter boundary values of the fouling surface, and sequentially solves the energy conservation equation, the momentum conservation equation, and the interphase heat transfer equation, and judges the convergence and rationality of the calculation results according to physical laws, and finally obtains the dry-out rate of the fouling layer, making the calculation results more accurate. The dry-out rate of the fouling layer calculated by this method is an important index for evaluating the risk of local cladding corrosion (CILC) in the fouling risk analysis of the reactor core. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Including the drawings is to provide a further understanding of the present application. They are incorporated and constitute a part of the present application. The drawings illustrate the embodiments of the present application and, together with this specification, serve to explain the principles of the present application. In the drawings:

[0032] Figure 1 is a flowchart of a dry-out rate calculation method for a fouling layer according to an embodiment of the present disclosure.

[0033] Figure 2 It is a schematic diagram of fouling layer division according to an embodiment of the present disclosure.

[0034] Figure 3 It is a schematic diagram of the capillary porous body structure according to an embodiment of the present disclosure.

[0035] Figure 4 is Figure 1 A flowchart of step S3 in an embodiment.

[0036] Figure 5 It is a system block diagram of a computing device according to an embodiment of the present disclosure. Detailed implementation manners

[0037] To more clearly illustrate the technical solutions of the embodiments of the present application, the accompanying drawings required for the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some examples or embodiments of the present application. For those of ordinary skill in the art, without creative efforts, the present application can also be applied to other similar scenarios based on these drawings. Unless obvious from the language context or otherwise stated, the same reference numerals in the figures represent the same structure or operation.

[0038] The present invention provides a method for analyzing the dry-out rate of a fouling layer required for fouling risk analysis. The method divides the fouling into grids, assumes the parameter boundary values on the fouling surface, sequentially solves the energy conservation equation, the momentum conservation equation, and the interphase heat transfer equation, and judges the convergence and reasonableness of the calculation results according to physical laws, and finally obtains the dry-out rate of the fouling layer. The dry-out rate of the fouling layer calculated by this method is an important index for evaluating the risk of local cladding corrosion (CILC) in the fouling risk analysis of the reactor core.

[0039] Figure 1 It is a flowchart of the method for calculating the dry-out rate of the fouling layer according to an embodiment of the present disclosure. As Figure 1 shown, the method 100 for calculating the dry-out rate of the fouling layer includes the following steps:

[0040] Step S1: Divide the fouling layer from the fouling surface to the wall surface in sequence.

[0041] Figure 2 It is a schematic diagram of fouling layer division according to an embodiment of the present disclosure. As Figure 2 shown, the grid is evenly divided according to the given fouling thickness δ, and the grid size is dx. The fouling layer is divided from the fouling surface (close to the fluid side) to the wall surface in sequence, and is respectively denoted as x(1), x(2),..., x(n), x(n + 1). x(n) represents the nth fouling layer. In particular, x(1) represents the first fouling layer, also known as the fouling surface. Among them The heat flux of the wall surface is transferred in the direction of the fluid. is the heat flux of the fluid.

[0042] Step S2: Set the interior of the fouling to be a capillary porous structure and set the parameter boundary values on the fouling surface.

[0043] The present disclosure sets the interior of the fouling to be a capillary porous structure. Figure 3 is a schematic diagram of a capillary porous structure according to an embodiment of the present disclosure. As Figure 3 shown, there is a set of interconnected pores in the porous body of this structure. These pores or the porous body can be divided into clusters of vertical pores and interconnected lateral pores. Assume that the larger vertical pores (r > critical effective radius R*) are filled with vapor, and the smaller pores (r < R*) are filled with liquid. For the lateral pores with a critical effective radius of R*, a dynamic equilibrium state is maintained between the liquid phase and the vapor.

[0044] The parameter boundary values refer to the boundaries of the effective range of the input parameters and the values near them. These values usually include the minimum value, the maximum value of the parameter, and the adjacent values of these values. For example, if the value range of a parameter is [1, 100], then the minimum value is 1, and the maximum value is 100. Then the effective boundary values are 1 and 100. The invalid boundary values are 0 and 101. The adjacent values are 2 and 99. Boundary value analysis is based on the assumption that instances tend to occur near the boundaries of the input range rather than in the middle. Optionally, the parameter boundary values on the fouling surface include but are not limited to the temperature of the fouling surface 、the critical pore radius 、the critical pore radius gradient 、the mass evaporation rate gradient .

[0045] The surface mass evaporation rate is obtained according to "the heat flux on the fouling surface must be equivalent to the heat flux on the wall surface ", and its mutual relationship is as shown in Equation .

[0046] (1)

[0047] In the formula: —the enthalpy value of the vapor phase on the fouling surface, with the unit of J / kg, where v represents the vapor phase;

[0048] —the enthalpy value of the liquid phase on the fouling surface, with the unit of J / kg, where l represents the liquid phase;

[0049] —the heat flux transferred by heat conduction, with the unit of W / m 2 .

[0050] Step S3: Construct a set of relational combinations for calculating flow and heat transfer parameters, and calculate the flow and heat transfer parameters of each fouling layer according to the relational combinations and the parameter boundary values of the fouling surface.

[0051] Among them, the relational combinations for calculating flow and heat transfer parameters include, but are not limited to, the energy conservation equation, the momentum conservation equation, and the interphase heat transfer equation. Optionally, calculating the flow and heat transfer parameters of each fouling layer includes inputting the parameter boundary values of the fouling surface into the relational combinations for calculating flow and heat transfer parameters, and recursively calculating the flow and heat transfer parameters of each fouling layer.

[0052] Optionally, the flow and heat transfer parameters include, but are not limited to, the mass evaporation rate, temperature, and critical pore radius.

[0053] Figure 4 Yes Figure 1 is a flowchart of an embodiment of step S3. As Figure 4 shown, step S3 includes:

[0054] Step S31: Construct the energy conservation equation and calculate the temperature of the n+1 layer according to the energy conservation equation.

[0055] This method believes that for the steady-state case, the energy transferred out of the fouling layer by conduction is equal to the net energy transferred into the fouling layer by the convection of the liquid and vapor. The relational expression of its energy conservation equation is as shown. Combining Fourier's law, as shown in the relational expression shown, the temperature of the n+1 layer of fouling can be obtained.

[0056] (2)

[0057] In the formula: —The heat flux under the conduction of the n+1 layer, unit: W / m 2 ;

[0058] is the heat flux under the conduction of the nth layer, unit: W / m 2 ;

[0059] is the mass evaporation rate of the n+1 layer, unit: kg / m 2 ·s;

[0060] is the mass evaporation rate of the nth layer, unit: kg / m 2 ·s;

[0061] is the enthalpy value of the vapor phase on the fouling surface, is the enthalpy value of the liquid phase on the fouling surface.

[0062] (3)

[0063] (4)

[0064] where: k is the thermal conductivity of the (n + 1)-th layer, and the subscripts crud, l, v, and s represent the fouling layer, the liquid phase in the fouling layer, the vapor phase in the fouling layer, and the solid phase in the fouling layer, respectively.

[0065] — the porosity of the (n + 1)-th layer;

[0066] — the proportion of the liquid phase in the (n + 1)-th layer in the fouling layer.

[0067] Optionally, before step S31, it further includes: inputting the temperature of the fouling surface into formula (3) to calculate the heat flux of the fouling surface , and judging whether the deviation between the heat flux of the fouling surface and the actually measured heat flux is greater than a preset threshold. If so, adjust the value of the temperature of the fouling surface.

[0068] Step S32: Construct a momentum conservation equation and calculate the critical pore radius of the (n + 1)-th layer according to the momentum conservation equation.

[0069] This method considers the variable fraction of the liquid phase filled in the fouling layer on the basis of Darcy's Law for porous media , adds a spatial acceleration phase to the momentum conservation equation, and its relational expressions are as and shown. Darcy's Law is the basic law describing the flow of fluids in porous media, proposed by the French engineer Henry Darcy in 1856. Darcy's Law shows that the flow velocity of fluids in porous media is proportional to the hydraulic gradient, and the proportionality coefficient is the permeability coefficient.

[0070] (5)

[0071] (6)

[0072] where: — pressure, unit is Pa, and the subscripts l and v represent the liquid phase and the vapor phase respectively;

[0073] — density, unit is kg / m 3 ;

[0074] — flow velocity, unit is m / s;

[0075] — Viscosity, unit: N·s / m 2 ;

[0076] — Permeability, unit: m 2 。

[0077] The difference between the vapor-liquid two-phase pressure gradients is as shown in the relational expression . Combining with the dynamic conservation equation, the critical pore radius gradient of the n+1 layer can be obtained 。

[0078] (7)

[0079] In the formula: — Liquid surface tension, unit: N / m;

[0080] — Contact angle, unit: °.

[0081] R* — Critical pore radius.

[0082] Optionally, before step S32, it further includes: calculating the critical pore radius of the n+1 layer and judging its rationality. Specifically, the critical pore radius , the critical pore radius gradient are input into the formula = to obtain the critical pore radius , and judge whether it is within the given pore radius range . If not, adjust the initial parameters: the values of the critical pore radius and the critical pore radius gradient .

[0083] Optionally, after step S32, it further includes: based on the Newton iteration method, judging whether the momentum conservation equation converges. If it does not converge, return to the step: calculating the critical pore radius of the n+1 layer and judging its rationality. When performing iterative calculations, the present disclosure adopts the Newton iteration method. In fact, different iterative convergence algorithms can also be used, which will not affect the calculation results.

[0084] Optionally, after step S32, it further includes: judging whether the critical pore radius gradient is positive. If it is negative, adjust the initial parameters: the values of the critical pore radius and the critical pore radius gradient .

[0085] Step S33: Construct the interphase heat transfer equation and calculate the mass evaporation rate of the n+1 layer according to the interphase heat transfer equation.

[0086] The equation of interphase heat transfer in the void is as shown in the relational expression As shown, by combining the momentum conservation equation, the mass evaporation rate gradient of the n+1 layer can be obtained.

[0087] (8)

[0088] Where: —Volume heat transfer coefficient of phase change, unit: W / m 3 ·K;

[0089] —Saturation temperature of the liquid inside the fouling, unit: K;

[0090] Is the temperature of the fouling layer, unit: K;

[0091] —Latent heat of vaporization, unit: J / kg.

[0092] According to the surface mass evaporation rate And the mass evaporation rate gradient of the n+1 layer The mass evaporation rate of the n+1 layer can be calculated. For example, the surface mass evaporation rate And the mass evaporation rate gradient Are input = , and the output ; Then according to the mass evaporation rate And the calculated mass evaporation rate gradient Calculate , and so on, to obtain the mass evaporation rate .

[0093] Optionally, before step S33, it also includes: setting the initial value of the mass evaporation rate gradient , and according to this value and the surface mass evaporation rate Calculate the mass evaporation rate , and judge whether it is within the preset range. If not, adjust the value of the mass evaporation rate gradient .

[0094] Optionally, after step S33, it also includes: based on the Newton iteration method, judge whether the interphase heat transfer equation converges. If not, return to the step: set the initial value of the mass evaporation rate gradient of the n+1 layer.

[0095] Step S4: Judge whether the current fouling layer is the dryout position according to the flow and heat transfer parameters. If so, obtain the thickness of the current fouling layer, and calculate the dryout rate of the fouling layer according to the thickness of the current fouling layer and the total thickness of the fouling layer.

[0096] Fouling accumulation will reduce the heat transfer efficiency, thereby reducing the evaporation rate. Optionally, when the mass evaporation rate of the fouling layer is lower than the first threshold and the temperature of the fouling layer is higher than the second threshold, the fouling layer is determined to be the dryout position. Calculate the dryout rate of the fouling layer according to Equation (9).

[0097] (9)

[0098] In the formula: — The thickness of the current fouling layer, in m;

[0099] — The total thickness of the fouling layer, in m.

[0100] The method for calculating the dryout rate of the fouling layer of the present invention has the following advantages:

[0101] 1. The present invention provides a method and system for analyzing the dryout rate of a fouling layer required for fouling risk analysis, constructs a set of relational expressions for calculating the dryout rate of the fouling layer on the surface of the fuel rods in the reactor core, and calculates parameters such as the temperature and mass evaporation rate of each fouling layer in detail according to the fouling characteristic parameters and fluid conditions, so as to obtain the dryout rate of the fouling layer, which helps to carry out the analysis of local cladding corrosion caused by fouling.

[0102] 2. In the present invention, by setting a reasonable analysis process and combining physical laws, a rationality judgment is set at an appropriate position in the analysis method process, which can save the number of iterations in the calculation process and obtain more accurate and reasonable calculation results.

[0103] 3. In the present invention, considering that the interior of the fouling is a capillary porous structure and considering the capillary action in the pores makes the calculation results closer to the reality.

[0104] 4. In the present invention, fine grids are divided for the fouling and the grid size is dynamically adjusted in the calculation process, making the calculation results more accurate.

[0105] In this application, flowcharts are used to illustrate the operations performed by the systems according to the embodiments of this application. It should be understood that the operations described above or below do not necessarily have to be performed precisely in order. On the contrary, various steps can be processed in reverse order or simultaneously. Also, one or more operations can be added to these processes, or one or more steps can be removed from these processes.

[0106] This application also includes a computing device, including a memory and a processor. Among them, the memory is used to store instructions executable by the processor; the processor is used to execute the instructions to implement the method for calculating the dryout rate of the fouling layer described above.

[0107] Figure 5 is a system block diagram of the computing device according to an embodiment of the present disclosure. Refer to Figure 5As shown, the computing device 500 may include an internal communication bus 501, a processor 502, a read-only memory (ROM) 503, a random access memory (RAM) 504, and a communication port 505. When the application is on a personal computer, the computing device 500 may further include a hard disk 506. The internal communication bus 501 may enable data communication among the components of the computing device 500. The processor 502 may make judgments and issue prompts. In some embodiments, the processor 502 may consist of one or more processors. The communication port 505 may enable data communication between the computing device 500 and the outside. In some embodiments, the computing device 500 may send and receive information and data from a network through the communication port 505. The computing device 500 may also include different forms of program storage units and data storage units, such as the hard disk 506, the read-only memory (ROM) 503, and the random access memory (RAM) 504, which can store various data files used for computer processing and / or communication, as well as possible program instructions executed by the processor 502. The processor executes these instructions to implement the main part of the method. The results processed by the processor are transmitted to the user device through the communication port and displayed on the user interface.

[0108] The above operation method may be implemented as a computer program, stored in the hard disk 506, and loaded into the processor 502 for execution to implement the dirt layer dry-burning rate calculation method of the present application.

[0109] The present application also includes a computer-readable medium storing computer program code, which implements the foregoing dirt layer dry-burning rate calculation method when executed by a processor.

[0110] When the dirt layer dry-burning rate calculation method is implemented as a computer program, it may also be stored in a computer-readable storage medium as an article of manufacture. For example, the computer-readable storage medium may include, but is not limited to, magnetic storage devices (e.g., hard disks, floppy disks, magnetic strips), optical disks (e.g., compact discs (CDs), digital versatile discs (DVDs)), smart cards, and flash memory devices (e.g., electrically erasable programmable read-only memories (EPROMs), cards, sticks, key drives). In addition, the various storage media described herein can represent one or more devices and / or other machine-readable media for storing information. The term "machine-readable medium" may include, but is not limited to, wireless channels and various other media (and / or storage media) that can store, contain, and / or carry code and / or instructions and / or data.

[0111] The basic concepts have been described above. Obviously, for those skilled in the art, the above invention disclosure is only an example and does not constitute a limitation to this application. Although not explicitly stated here, those skilled in the art may make various modifications, improvements, and corrections to this application. Such modifications, improvements, and corrections are proposed in this application, so such modifications, improvements, and corrections still fall within the spirit and scope of the exemplary embodiments of this application.

[0112] Meanwhile, this application uses specific terms to describe the embodiments of this application. Such as "one embodiment", "an embodiment", and / or "some embodiments" mean a certain feature, structure, or characteristic related to at least one embodiment of this application. Therefore, it should be emphasized and noted that the "one embodiment" or "an embodiment" or "an alternative embodiment" mentioned twice or more at different positions in this specification does not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of this application can be appropriately combined.

[0113] Some aspects of this application can be executed entirely by hardware, can be executed entirely by software (including firmware, resident software, microcode, etc.), or can be executed by a combination of hardware and software. The above hardware or software can all be referred to as "data blocks", "modules", "engines", "units", "components", or "systems". The processor can be one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DAPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, or combinations thereof. In addition, aspects of this application may be embodied as a computer product located in one or more computer-readable media, which includes computer-readable program code. For example, computer-readable media can include, but are not limited to, magnetic storage devices (such as hard disks, floppy disks, magnetic tapes...), optical discs (such as compact discs CD, digital versatile discs DVD...), smart cards, and flash memory devices (such as cards, sticks, key drives...).

[0114] The computer-readable medium may contain a propagated data signal that contains computer program code, for example, on a baseband or as part of a carrier wave. This propagated signal may have various forms of manifestation, including electromagnetic form, optical form, etc., or a suitable combination of forms. The computer-readable medium can be any computer-readable medium other than a computer-readable storage medium, which can be connected to an instruction execution system, apparatus, or device to implement communication, propagation, or transmission for use of the program. The program code located on the computer-readable medium can be propagated through any suitable medium, including radio, cable, fiber optic cable, radio frequency signal, or similar media, or any combination of the above media.

[0115] Similarly, it should be noted that, in order to simplify the description of the disclosure of the present application and thus help the understanding of one or more embodiments of the invention, in the foregoing description of the embodiments of the present application, sometimes multiple features are grouped into one embodiment, drawing or description thereof. However, this method of disclosure does not mean that the features required by the subject matter of the present application are more than the features mentioned. In fact, the features of the embodiments are fewer than all the features of the single embodiments disclosed above.

[0116] As shown in the present application, unless the context clearly indicates an exception, words such as "a", "an", "one" and / or "the" are not specifically singular and may also include the plural. Generally speaking, the terms "comprising" and "including" only indicate the inclusion of the steps and elements that have been clearly identified, and these steps and elements do not constitute an exclusive list. The method or device may also include other steps or elements.

[0117] Unless otherwise specifically stated, the relative arrangements, numerical expressions and values of the components and steps set forth in these embodiments do not limit the scope of the present application. At the same time, it should be understood that, for the sake of convenience of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship. Technologies, methods and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the said technologies, methods and devices should be regarded as part of the description. In all the examples shown and discussed here, any specific value should be construed as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that: like reference numerals and letters denote like items in the following drawings, and thus, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0118] In some embodiments, numbers describing the composition and quantity of properties are used. It should be understood that such numbers used in the description of the embodiments are modified by the modifiers "about", "approximate" or "substantially" in some examples. Unless otherwise stated, "about", "approximate" or "substantially" indicate that the said numbers allow a variation of ±20%. Accordingly, in some embodiments, the numerical parameters used in the description are approximate values, and the approximate values may change according to the characteristics required by individual embodiments. In some embodiments, the numerical parameters should consider the specified significant digits and adopt the method of retaining the general number of digits. Although the numerical ranges and parameters used to confirm the breadth of the scope of some embodiments of the present application are approximate values, in specific embodiments, the setting of such numerical values is as accurate as possible within the feasible range.

[0119] Although the present application has been described with reference to the current specific embodiments, those of ordinary skill in the art should recognize that the above embodiments are only used to illustrate the present application, and various equivalent changes or substitutions can be made without departing from the spirit of the present application. Therefore, as long as the changes and modifications of the above embodiments are within the scope of the spirit of the present application, they will fall within the scope of the present application.

Claims

1. A method for calculating the burnout rate of a dirt layer, characterized in that: include: Dirt layers are divided sequentially from the dirt surface to the wall surface; Set the dirt interior to a capillary porous structure and set the parameter boundary value of the dirt surface; Constructing a set of relational expressions for calculating flow heat transfer parameters, and calculating the flow heat transfer parameters of each fouling layer according to the relational expressions and the parameter boundary values ​​of the fouling surface; Determine whether the current dirt layer is at a burn-out position according to the flow heat transfer parameter, and if so, obtain the thickness of the current dirt layer, and calculate the burn-out rate of the dirt layer according to the thickness of the current dirt layer and the total thickness of the dirt layer; Wherein, the flow heat transfer parameters include mass evaporation rate, temperature and critical pore radius, and the relationship combination includes: momentum conservation equation, energy conservation equation and interphase heat transfer equation; The momentum conservation equation is: in, is the surface tension of the liquid, is the contact angle, is the critical pore radius, P is the pressure, subscripts l and v represent the liquid phase and vapor phase, respectively, and x is the thickness parameter of the fouling layer; The energy conservation equation is: in, is the heat flow under the heat conduction of the n+1th layer, is the heat flow under the heat conduction of the nth layer, is the mass evaporation rate of the n+1th layer, is the mass evaporation rate of the nth layer, is the vapor phase enthalpy of the dirt surface, is the liquid phase enthalpy of the dirt surface, is the difference between the liquid phase enthalpy of the dirt surface at the n+1th layer and the vapor phase enthalpy of the dirt surface, is the difference between the liquid phase enthalpy of the dirt surface at the nth layer and the vapor phase enthalpy of the dirt surface; The interphase heat transfer equation is: in, is the volume heat transfer coefficient of phase change, is the saturation temperature of the liquid inside the dirt, is the temperature of the dirt layer, is the latent heat of vaporization, is the mass evaporation rate, and x is the thickness parameter of the dirt layer.

2. The method for calculating the burnout rate of the dirt layer according to claim 1, characterized in that: The temperature of each dirt layer is calculated by the following formula: in, is the thermal conductivity of the dirt layer, is the temperature of the dirt layer, and x is the thickness parameter of the dirt layer.

3. The method for calculating the burnout rate of the dirt layer according to claim 2, characterized in that: The thermal conductivity of the dirt layer is calculated by the following formula: in, is the porosity of the n+1th layer, is the ratio of the liquid phase in the n+1th layer to the dirt layer, k is the thermal conductivity, and the subscripts l, v, and s represent the liquid phase in the dirt layer, the vapor phase in the dirt layer, and the solid phase in the dirt layer, respectively.

4. The method for calculating the burnout rate of the dirt layer according to claim 3, characterized in that: Based on Darcy's law for porous media, the proportion of the liquid phase in the fouling layer A variable value.

5. The method for calculating the burnout rate of the dirt layer according to claim 1, characterized in that: When the mass evaporation rate of the dirt layer is lower than a first threshold and the temperature of the dirt layer is higher than a second threshold, it is determined that the dirt layer is at a burnt-dry position.

6. The method for calculating the burnout rate of the dirt layer according to claim 1, characterized in that: Also includes: In the process of calculating the flow heat transfer parameters, the convergence and rationality of the calculation results are judged according to physical laws to save the number of iterations in the calculation process.

7. The method for calculating the burnout rate of the dirt layer according to claim 1, characterized in that: Also includes: In the process of calculating the flow heat transfer parameters, the grid size is dynamically adjusted.

8. The method for calculating the burn-off rate of a dirt layer according to any one of claims 1 to 7, characterized in that: The parameter boundary values ​​of the fouling surface include: the temperature of the fouling surface, the critical pore radius, the critical pore radius gradient and the mass evaporation rate gradient.

9. A computing device, characterized in that: include: at least one processor; as well as At least one memory having instructions stored thereon, wherein when the instructions are executed individually or collectively by the at least one processor, the computing device executes the method as claimed in any one of claims 1 to 8.

10. A computer-readable medium, characterized in that The computer-readable medium stores instructions, which, when executed individually or collectively by at least one processor of a computing device, cause the computing device to execute the method as claimed in any one of claims 1 to 8.

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